End dog and multiple saw sawmill



Aug. 20, 1957 J. D. CROSBY, JR

END DOG AND MULTIPLE SAW SAWMILL 3 Sheets-Sheet 1 Filed Nov. 23. 1953Inventor Attorney Aug. 20, 1957 J. D. CROSBY, JR

END DOG AND MULTIPLE SAW SAWMILL 3 Sheets-Sheet 2 Filed NOV. 25. 1953 IInventor Attorney 1957 J. D. CROSBY, JR 2,803,272

' END DOG AND MULTIPLE sAw SAWMILL Af/orney n ed S a Pa en END DOG ANDMULTIPLE SAW SAWMILL John D. Crosby, Jr., Bay Minette, Ala., assignor often percent to A. Yates Dowell, Washington, D. C.

Application November 23, 1953, Serial No. 393,901 6 Claims. (Cl. 14337)This present invention relates to the processing of timber and moreparticularly to a sawmill for supporting a log centrally at both of itsends and while the log is so supported the entire sawing operation isperformed.

Heretofore, sawmills have been operated in which a more or lessconventional carriage moved the log past a single saw blade and only oneedge of the log could be sawed at a time requiring four passes and aquarterturn between each pass of the log to produce a square timberwhile the sawyers were required to ride the carriage back and forth withthe logs for securing the log to the carriage and turning the log at therequired time. This procedure required an excessive amount of time withthe tedious work of riding the cars at high speeds and accelerationresulting in detrimental effects upon the workmen. Further, themechanism for performing the turning of the log was very complicated andrequired substantial force applied to the log with some danger ofdamaging a surface of the finished lumber and thereby reducing itsvalue.

7 An object of the present invention is to overcome the defects of theconventional practice and to provide a sawmill which can be operatedwith a minimum of skilled labor and amount of manual labor.

Another object of the invention is to provide a structure for supportinga log so that a single step of securing the log to the carriage is theonly requirement for semiskilled labor.

Another object of the invention. is to provide a sawmill structure whichcan be assembled from standard parts with the resulting saving ininitial and upkeep costs. Another object is to provide means for shapinga blank where one operator has. full control of the shaping operation.

A further object of the invention is to increase the efficiency of thecombination of labor and capital in the production of lumber.

Briefly stated, the invention includes an overhead track on which acarriage is mounted for movement from a loading position through theshaping or sawing position and capable of receiving a log from theloading position and discharging the sawed log upon completion of theshaping operation thereon. Adjacent the loading station are a first pairof saws spaced apart to simultaneously saw both sides of a log and asecond pair of saws located in the path of movement of the log forthereafter making a further cut in the portion of the log remainingbetween the first two saws. Each pair of saws is adjustable with atleast one pair being adjustable by power means.

For supporting a log, the carriage is provided with a pair of downwardlyextending brackets with at least one bracket movable, toward and fromthe other. Each bracket is provided with a center similar to the typesused on lathes and supports a log by engaging each end thereof and meansare provided for rotating one center and thereby the log a quarter of aturn for producing a right angle cut on the other opposed sides. Anauxiliary supporting roller hydraulically movable from operative 203,272 Patented Aug. 20, 1957 to inoperative position and vice versa, isprovided between the pairs of saws to prevent undesired bending andvibration of the partially sawed log.

A loading and elevating structure is provided for receiving one log at atime and raising such log to the centers on the brackets so that thebrackets may be moved toward each other projecting the centers into thelog ends thereby supporting the same for the sawing operation. Suitablecompressed air and hydraulic cylin- 0 ders are provided for controllingthe various operations and the sawyer controls the entire sawmill exceptfor the loading elevating structure, which is controlled by a workmanwho also sees that the log is properly located on the centers.

Further objects and advantages of the invention will be apparent fromthe following description taken in conjunction with the drawings,wherein:

Figure 1 is a plan view of the sawmill with parts broken away and partsomitted showing the relation of the saw blades and their supportingframes to the overhead tracks, traveling carriage and the loadingelevating structure;

Fig. 2, a side elevation with part broken away and parts omitted showingthe elevator in log receiving position, the carriage in position forreceiving a log, and the conveyor structure for removing the sawedlumber;

Fig. 3, sheet 1, a side elevation of the elevating and loading frame; 7

Fig. 4, a plan view of the elevating frame;

Fig. 5, sheet 2, a fragmentary section taken substantially on line 55 ofFig. 1; and

Fig. 6, a diagrammatic view showing the air controls for clamping androtating the log on the carriage; and

Fig. 7, a diagrammatic view showing the hydraulic system for moving thecarriage, adjusting the saws toward and away from each other, elevatingthe log, and moving the supporting roller in position for the last passof 'th lumber.

Referring more particularly to the drawings wherein like referencednumerals refer to like parts throughout, a carriage 10 supported bywheels 12 is mounted for movement on tracks 13, 13' supported by I-beammembers 14 which are mounted on supporting posts 15, 15'/-16, 16 and aplurality of other posts not shown, so that the carriage is movable inan elevated plane. To the right of the posts 16, 16' bed frames 17, 17'are mounted, which frames are partially supported by the posts 16, 16'and other supporting means such as legs 18 and 19. Upon the bed frames17, 17 are mounted adjustable sawcarrying slide frames 20, 20 and 21, 21which frames are movable a limited amount toward and from the centerline of the sawmill and of the carriage. The movable saw-carrying frames20 and 21 at the front of the mill are similar to movable frames 20' and21 at the back of the mill. A log loading and elevating frame 22 ispositioned beneath the overhead tracks 13 and to the left of thesaw-carrying slide frames 20, 20, 21, 21' in a position for loading thelog onto the log-carrying centers of the carriage.

ing axles 30 and spaced therebelow is a longitudinally extending shaft31 which is secured to cross members 33, 34 fixedly mounted on the undersides of the frame members 11, 11 and fixed to the longitudinal shaft bysuitable means such as U-bolts or bearing caps 35, 35 and/or by welding,the right end of the shaft being supportedby a downwardly extending arm36 fixed to the leading cioss" member 26 and the lower end of arm 36includes a U- shaped clamp such as a bearing cap 37 for supporting suchleading end. A Z-shaped bracket 38 having its inter mediate portionhorizontal with a longitudinal bore in the horizontal portion thereof isslidably mounted with its bore surrounding the leading end of shaft 31and has an upwardly extending arm 39 projecting above the frame 11 and adownwardly extending arm 40 rotatably supporting a center 41 at thelower end thereof. Such center may be of conventional design and isshown as including three circumferentially spaced chisel projections forengaging the center of the end of a log. The Z-shaped bracket 33 isprevented from swinging movement about longitudinal shaft 31 by anglemembers 42, 42' mounted on the upper surfaces of transverse framemembers 25 and 26 and such angle may carry rectangular shaped guide bars43, 43 extending between the transverse frame members 25 and 26 andslidably engage the upwardly extending arm 39 of the Z-shaped bracketthereby preventing swinging movement of the bracket 38 about shaft 31.The bracket 38 may be moved from its full line position to its dottedline position (Fig. 2) by means of a pneumatic cylinder 44 pivotallysecured at one end to an upwardly extending lug 45 projecting fromtransverse frame member 24 with a brace 46 secured to another transverseframe member such as 33. The piston rod 47 is provided with a yoke atits outer end which embraces the upstanding arm 39 of the Z-shapedbracket 38 and is pivotally secured thereto by a pin 48. The Z-shapedbracket 38 can thereby be moved longitudinally on the carriage by theapplication of air pressure to the ends of the cylinder 44 byconventional air hoses as hereafter described.

A second Z-shaped bracket 49 includes a central portion with a boreslidably received on the trailing end of longitudinal shaft 31 and theupstanding arm 50 thereof extends between transverse angle members 27and 28 and is secured thereto by set screws 51, 51 or other suitablemeans mounted on transverse angle members 27 and 28, thereby preventingswinging movement of the Z-shaped bracket 49. The downwardly extendingarm 52 is provided with a tubular bearing 53 in which is mounted arotatable center 54, similar to center 41, for engaging the trailing endof the log. An extension 55 of the horizontal portion of the bracket 49is of L-shape and lies in a substantially horizontal plane for pivotallysupporting one end of a pneumatic cylinder 56 (Fig. 1). In the verticalplane of the centers 41 and 54 is a shaft 57 (Fig. 2) connected to thetrailing end of center 54 by means of a universal joint 58 and suchshaft 57 is rotatably mounted in a bearing 59 (Fig. l) on the L-shapedextension 55. Such shaft 57 includes a crank arm 60 fixed thereto andwhich is pivotally connected at its free end to the piston rod 61whereby the pneumatic cylinder 56 may rotate the shaft 57 and therebythe center 54 a fixed amount which is preferably 90. Such rotation maybe limited by providing suitable stops 62, 63 for limiting the rotationof the center 54, and if desired, such stops may be made adjustable byany suitable means such as a screw or the like. A fixed stop built up tothe proper ext nt by welding has been found to be satisfactory.

For propelling the carriage, an elongated cylinder 63 (Figs. 1 and 7) isfixed at its left to a support, (not shown) and the projecting pistonrod 64 is pivotally connected to a downwardly extending arm 65 mountedon the leading end of the carriage. It will be evident that the cylinder63 and the piston rod therein are of suflicient length to move thecarriage the desired distance by means of fluid pressure such ashydraulic pressure.

It will be evident that the carriage may be controlled in its movementby the control of the hydraulic cylinder 63 and the securing of the logbetween the centers may be accomplished by means of the pneumaticcylinder 44 which moves the Z -shaped bracket 38. The log may be rotateda fixed amount by means of the pneumatic cylinder 56. The carriage maybe reversed end for end if desired, and a safety feature is provided inthe form of track embracing guides 66 and 66' fixed to the carriagepartially surrounding the tracks to avoid danger of the carriage jumpingthe track. The supply of air to cylinders 44 and 56 may be provided bymeans of air hoses which may be supported by means of a spring suspendedat a relatively high location in the building or other structure andpositioned rearwardly of the carriage to permit the latter to move fromone end of the tracks 13 past the sawing station and to the dischargeposition for the finished lumber and such arrangement is not shown indetail to avoid unnecessarily complicating the drawings.

Log loading and elevating structure Referring to Figs. 1 to 4 of thedrawing, a pair of up standing Y-shaped members 67, 67A are arranged inspaced relation between the supporting posts 15 and 16 and below thetracks for receiving logs thereon and upstanding abutment posts 68, 68Aprojecting from the ground to above the Y-shaped member 67 prevent logsfromrolling olf rearwardly from the Y-shaped members. Upwardly extendingbraces 69, 69A serve to reinforce the upwardly and forwardly extendingleg of the Y-log supports 67, 67A respectively and upon the upper end ofsuch braces 69, 69A are mounted socket or angle members 60, 60A, uponwhich angle members one end of rails 71, 71A are mounted, the other endsof such rails extending to a supply of logs so that logs 72, may rolland/or slide on such rails to the Y-supports 67, 67A.

Between the Y-supports 67 and 67A is mounted a trapezoidal shaped frame73 which is pivoted at its smaller or rear end to an upstanding frame 74which is braced by struts 75 and the trapezoidal frame being pivotallymounted by any suitable means such as lugs and pins 76 of well knowndesign. The forward ends of the side frame members are arranged insubstantially parallel relation and support inverted A-shaped cradles77, 77A, which cradles are substantially in registry with the upstandingarms of the Y-shaped frames 67, 67A whereby a log may roll down rails71, 71A and into the Y-supports and inverted A-shaped cradles. The frame73 is raised from its full line to its dotted line position by means ofa hydraulic cylinder 78 which is pivotally connected at one end to thelower extremity of struts 75 with a piston rod 79 thereof beingpivotally connected to a transverse member 86 extending between thenonparallel sides of the trapezoidal frame 73 whereby the trapezoidalframe 73 with the inverted A-shaped cradles may be moved from the fullline to the dotted line positions shown in Fig. 2. To prevent excessivemovement of frame 73 suitable stops 81, 81A may be provided on theY-shaped log supporting members for limiting the downward movement andother suitable stops may be provided to limit the upward movement toprevent the inverted A-cradles from lying in the path of movement of thelog supporting centers 41 and 54. The hydraulic cylinder 78 iscontrolled by means, of a four-way valve 82 located adjacent the post16, for operation by a workman whose duty is to see that a log isproperly located on the inverted A-shaped cradle 77, 77A to raise suchlog so that it lies between the centers 41 and 54, and to manually movethe log on the horizontal bar 83 of the inverted A-shaped cradles sothat at least one center 54 or 41 is accurately located with the centerof the log. At this time, the sawyer who has control of all the otheroperations of the mill may move the carriage to cause center 54 toengage the trailing end of the log, thereafter the center of the leadingend of the log is properly positioned with relation to the center 41 atwhich time the sawyer moves the movable log supporting bracket 38 intoengagement with the leading end of the log, thereby securing the log onthe carriage ready for the sawing operation, elevating frame 22 beingpivotally mounted at one side and having the power operating cylinder 78exerting its force substantially midway between the ends of the frameand the frame being relatively flat, provides some flexibility of theframe and in positioning the log between the centers 41 and 5 theelevator may be raised to approximately position the log at the correctelevation and at that time the operator may grasp one end of the log andaccurately position. such one end in proper relation to its center andthe center is then moved against the log so as to retain the log on thecenter after which the other end of the log is similarly positioned andby the operation of the cylinder 44 the centers are moved togethergripping the log therebetween. The flexibility of the elevating frame isillustrated in phantom lines showing exaggerated positions of the logclosely adjacent downwardly depending brackets 40 and 52. It will alsobe evident that the logs can be rolled or slid across bars 33 of theinverted A-shaped cradles since the log is normally of smallertransverse dimension than the spacing between the legs of the A-shapedcradle.

Saw carrying slides and discharge conveyor A first pair of saw blades 84and 84' are mounted on conventional arbors 85, 85' which arbors arerotatably mounted in bearings 86, 86 mounted on the slide frames 20, 20'respectively which slide frames are mounted for movement toward and fromone another by a slidable mounting with relation to the bed frames 17,17, respectively. For guiding the frames for rectilinear movementparallel with the arbors, guide bars 87, 87 are mounted on the undersideof frame 20 and guide bars 88, 88' cooperating therewith are mounted onthe upper side of bed frame 17 (see Fig. 5.) Similar bars are providedon the other slide frames for accurately guiding such other frames.

For moving the saw blades 84 and 84' toward and away from one another,hydraulic cylinders 89, 89' are mounted for reaction between the bedframe 17, 17' and the slide frames 20 and 20' respectively and referringto Fig. 5, one arrangement for accomplishing this connection is shown toinclude an L-shaped bracket 90 having its longer leg fixed to the outerportion of bed frame 17 and extending therefrom inwardly toward the sawblade and then projecting upwardly at which point a piston rod 91 ispivotally connected to the L-shaped bracket 90 and the cylinder 89 ispivotally connected to the slide frame 20 whereby the application offluid pressure in the cylinder 89 will cause the slide frame 20 to movein the required direction. The two hydraulic cylinders 89 and 89 areconnected in parallel and operated by a single control valve 92 of the4-way type (upper center of Figure l) and suitable stops are providedfor limiting the movement of the frames 20 and 20' in both directionsand such stops may take any desired form such as a pair of upstandingyokes fixed to the bed frame 17 and a cooperating projection on theframe 20 for cooperation with each of said yokes and each of the yokesmay be provided with an adjusting screw for accurately controlling theextent of movement of the frame 20 in its sliding movement. Similarly,the frame 20' may be provided with stops limiting its movement and bythe hydraulic control the sawyer can vary the width of the outsideboards in accordance with the dimension of the log being sawed.

Although saw frames 21 and 21' are mounted for sliding movement, it hasbeen found that a fixed adjustment for the slide frame is satisfactoryand such fixed adjustment may be accomplished by means of straps 93(Figure 1) located above the slide frame 21 and below a cross member inbed frame 17 with connecting bolts 94 arranged to have their lower endscloser to the saw blades 95, 95' for preventing outward sliding movementof the slide frames 21 and 21' and such straps 93 and bolts 94 permitadjustment as necessary. It will be evident that hydraulic cylinderscould be used for moving the slides 21 and 21' similar to the hydrauliccylinders shown for slides 20 and 25, if desired, and suitable stops canalso be provided.

The saws 95, 95' are mounted upon mandrels or arbors 96, 96 which arerotatably mounted in bearings 97, 97' and the mandrels 96 and 96 carrybelt pulleys 98, 98 of substantial Width which are driven by means ofbelts 99, 99' from a suitable source of power and the pulleys 98 beingsubstantially wider than the belts 99 permit sliding movement of theslide frames without affecting the driving relation. Similarly, mandrelsand 85 are provided with a drive pulley 100 and 100' which are driven bybelts 101, 101' from a suitable source of power.

When a log supported on centers 41 and 54 is passed between the sawblades 84, 84 and 95, 95', a first cut is made by the saws 84, 84removing the slabs or outside portions of the log and the saws 95 and 95cut boards of a width equal to the lateral spacing of saws 84, 95, and84, 95 and upon completing the pass, beyond the left edge of saws 84,84' the outer slabs are completely severed from the log and uponcompleting the pass beyond the left edge of saws 95 and 95', the boardsformed by the cuts of the two pairs of saws are completely severed. Thefiat center section of the log from top to bottom remains supported onthe center 41 and 54 and such center portion of the log is returned tothe position of the carriage shown in full line where such centersection is rotated through and then such center section is passedbetween the saws 84, 84' and 95, thereby cutting the remaining slabs andboards from the side of the center section which had previously been atthe top and bottom of the log.

For removing the slabs and the board cut from the log, suitableconveying structure is provided and such conveying structure is shown atthe rear of the-mill in Fig. 1 and is shown in partial elevation withparts omitted in Fig. 2. The forward set of conveyors has been omittedin Fig. 1 so that the structure therebeneath could be more clearlyshown. For uniform numbering the conveyor at the rear side of the millwill be designated with the prime added thereto.

A plurality of idle rollers 102' are rotatably mounted on side framemembers 103', 104' mounted on slide frame 20' and similar rollers 102are mounted on slide frame 20. The supports for such rollers may takevarious form including individual upstanding lugs if desired.

Similarly rollers 105' are mounted for rotation on side frame members106', 107' which members are mounted on slide 21 whereby the rollersmove with the slides similar to the movement of the rollers 102 with theslide 20'. It will be evident that similar rollers 102 and 105 aremounted respectively on supporting frame members upon slides 20 and 21respectively.

A guard 108 is provided adjacent each saw blade to prevent any danger ofthe board dropping between the saw and the rollers and such guard isinclined to assist in directing the board to the rollers 102, 102, 105,105. Extending from the right end of the saws 95, 95' is a more or lessconventional belt conveyor 109 for carrying the lumber after it is fedthereto by the rollers or after the last center piece supported directlyby the centers 41 and 54 is dropped from the carriage upon separation ofthe Z-shaped bracket 40 from bracket 52. Adjacent the conveyor 109 aremounted rollers 110, 111 and another guide roller 112 is mounted inframer 20 and a lower guide roller 113 is mounted in suitable positionfor guiding a drive belt 114 which passes around guide rollers 110, 111,112, and 113, and such drive belt engages the underside of idle conveyorrollers 105 and 102, such belt 114 being driven by the arcuate contactwith conveyor 109 in the direction indicated by the arrows therebycausing the rollers 102 and 105 to feed lumber thereon toward conveyor109 for discharge.

Intermediate log support During the first pass of the log between thesaws the 7 strength of the entire log serves to prevent undue bendingthereof and the sawing operation can be performed satisfactorily withoutsupporting the log intermediate its ends. However, during the secondpass of the log the flat center portion is of a thickness equal to thespacing between the saw blades 95 and 95'. When the saws 95 and 95' arecutting the center portion of the relatively flat blank, that portion ofthe log is supported solely by a rectangular section having thedimensions corresponding to the spacing of saw blades 95 and 95 andtherefore such portion of the blank is relatively weak and substantialbending and vibration takes place. To overcome this problem a supportingroller 115 is rotatively mounted in a vertical strut member 116 which ispivotally mounted at its lower end by suitable lugs and pivot pin to across-channel frame member 117 extending between the inner portions ofbed frames 17 and 17' and the mounting is such that the roller 115 willcontact the lower surface of the flattened blank when the strut androller supported thereon are in the full line position shown in Figs. 1and 2, while such strut may be moved to the dotted line position shownin Fig. 1 to permit the free passa e of the log or blank during thefirst pass thereof. arm 118 secured to the strut is pivoted to a pistonrod 119 of a hydraulic cylinder 120 which has its outer end pivotallymounted to a cross-frame member 121 whereby the roller 115 can be movedfrom its operative full line position to its inoperative position bymeans of hydraulic cylinder 12% under the control of the sawyer. Toprevent excessive movement of the roller and strut 115, a cross-framemember in the form of an I-beam 121 may be provided which is suitablysupported from the main frames 17 and 17' and, if desired, suitableadjustments may be provided to limit the movement and verticaladjustment of the roller. It has been found necessary to remove part ofthe web of the I-beam 121 for passage of arm 118 to the lowered positionof roller 115. The stops may be built up by welding if desired.

Hydraulic and pneumatic control From the above description it will beevident that the logs are fed from a supply on supporting rails 71, 71Ato the inverted A cradles on the loading and elevating frame 73 and suchlogs are guided thereto by means of the .--shaped log supports 67, 67A.Assuming the carriage 1b to be in approximately the position shown, aworkman positioned adjacent the post 16 controls the raising ofelevating and loading frame 73 by means of valve 32 which controls thesupply of hydraulic fluid to hydraulic cylinder '78, whereby the log maybe accurately raised so that the centers thereof are approximately atthe height of the centers 41 and 54 of the carriage, whereupon the sameworkman with one hand may engage the log to center one end properlythereof in the center 54, for example, and the sawyer located adjacentpost 16 may move the carriage so that center 54 will engage the log andthereafter the workman may accurately position the leading end of thelog and the sawyer at that time will cause the Z-shaped bracket 38 to bemoved toward fixed bracket 52 thereby clamping the log on the centers 41and 54. The elevating and loading frame 73 is somewhat flexible so thatthe workman may bear down on one end and thereby raise the other end ofthe frame or vice versa for accurately positioning the log with relationto the centers. The horizontal bar 83 of the inverted A cradles permitssome rolling of the log to assist further in positioning the logforwardly or rear wardly so the workman need only guide the log withoutrequiring any appreciable physical exertion. A fourway valve 122 (Figs.1 and 6) controls pneumatic cylinder 44 for gripping the log and thefour-way valve 123 controls hydraulic cylinder 63 for moving thecarriage forwardly and rearwardly.

Assuming the log is loaded on the centers 54 and 41 with the sawsrunning, the sawyer operates valve 123 (Figs. land 7.) causing thepiston .rod 64 to project out of hydraulic cylinder 63 and move thecarriage 10 with the log past the saws 84, 84 and 95, at which time theslabs are separated by the first pairs of saws and boards are formed bysaws 95 and 95 while the center portion of the log becomes a relativelyflat blank and the slabs and boards are carried from the saws by therollers 102, 102, 105, 135, which are continuously rotated by means ofthe belt 114 driven by the continuously operating discharge conveyor109.

The carriage is then returned to its full line position under thecontrol of the sawyer by controlling valve 123 and after the flat blankhas cleared the saws, the sawyer operates a valve 124 (Figs. 1 and 6),which actuates pneumatic cylinder 56 and rotates the flat blank through99 and the carriage is then operated by means of valve 123 and hydrauliccylinder 63 to carry the now horizontally positioned flat blank past thesaw blades. At this time the sawyer also actuates valve 124A (Figs. 1and 7) which controls hydraulic cylinder to move the guide roller 115 toits full line position and the upper surface of roller 115' issubstantially at the height of the lower surface or" the horizontallypositioned flat blank and engages such flat blank at a point adjacentthe cutting region of saws 95, 95, where the downward reaction on theflat blank is greatest for supporting the flat blank and particularlythe center section thereof. This avoids objectionable bending andvibration due to the small size of the square center section of the log.Such center sections have been approximately 4 inch by 4 inch beams andat the center of the unsupported flat blank the bending moment becomesexcessive. However, with the roller 115 in position, the objectionablevibration and bending has been avoided. It will be noted that pneumaticcylinder 44 is continuously supplied with air pressure so that the logis continuously under the axial pressure produced between centers 54 and41, thereby avoiding any danger of the log or blank dropping from thesupports.

After the carriage has moved the horizontally positioned flat blank pastboth pairs of saws, the control valve 122 is actuated to operatepneumatic cylinder 44 and separate center 41 from center 54, therebypermitting the sawed center section to drop and it will be evident thatthe slabs and boards which have been sawed are carried by the rollers162, 102', 105, 105' to conveyor 109 to the place of grading or storageof the lumber or to a vehicle for carrying such lumber to a location forgrading and/or storing. The carriage is then returned to its positionfor receiving another log and the valve 124 may either be left in itspresent position or restored to its initial position thereby rotatingthe center 54 as desired.

In the event that it is desired to vary the thickness of the board cutbetween saw 84 and saw 95 or between saw 84 and saw 95, the valve 92 maybe actuated to energize hydraulic cylinders 89 and 89' in the desireddirection to increase or decrease the thickness of the boards. It willbe observed that hydraulic cylinders 89 and 89 are simultaneouslysupplied with hydraulic fluid through conduits 125 and 126. It will beevident that suitable stops may be provided to limit the movement of theslide frames 20 and 20 and such stops may be adjustable. Further, insome situations it may be desirable to control the hydraulic cylinders39 and 89' individually, thereby sawing a thick board on one side and athin board on the other.

Compressed air is furnished to a supply line 127 (Fig. 6) from apressure tank 123 supplied by a motor compressor unit 129 ofconventional construction, and the exhaust air may be removed to anydesired location by an exhaust conduit 13%) or such exhaust duct may beomitted and the air discharged at the valves 122 and 124 directly intothe atmosphere.

The hydraulic system includes a hydraulic pump 131 (Fig. 7) which maysupply hydraulic fluid to a pressure tank 132 which may have compressedair in the upper portion thereof or the hydraulic fluid may be feddirectly from the pump 131 to a supply conduit 133, which is providedwith suitable branch lines to the various valves 92, 123, 124A,controlled by the sawyer and to valve 82 controlled by the workmanloading the carriage. Suitable return conduits from the varioushydraulic valves are in communication with return duct 134 from whichduct the hydraulic fluid is collected in a pump 135 which is connectedto the inlet of hydraulic pump 131.

It will be evident that the conduits for the hydraulic fluid are madeflexible where necessary and the hydraulic system will includeconventional safety precautions such as by-pass means for preventingexcessive pressures in the system. The supply of air to the cylinders 44and 56 has been accomplished by means of flexible hoses suspended from apoint substantially above the carriage and to the rear thereof by meansof a long coil spring to permit the necessary movement of the carriagewithout interference and since the control cylinders on the carriage arepneumatically actuated, there is no danger of loss of hydraulic fluidand the weight of the supply lines is appreciably less with air thanwith hydraulic fluid. Also, the pneumatic pressure is continuousregardless of any slight variations in the length of the log or in thepenetrating action of the centers, since such pneumatic pressure willtake up anyvariation.

Although the structure has been described as being for one length oflogs, it will be observed that the trailing Z-shaped bracket 49 can beadjusted along the trailing end of shaft 31 by changing the location ofangle members 27, 28 by removing bolts 29 and providing additional holesin the side frame members 11 of the carriage 10. The L-shaped support55' secured to the Z-shaped bracket 49 will move therewith during suchadjustment. In some installations it may be that the movement of Z-shaped bracket 38 would take care of the necessary variation in loglengths and the Z-shaped bracket 49 may be fixed. In such situations,the pneumatic cylinder 56 may react between the frame 11 and the arm 60of the shaft 57 for producing the quarter turn rotation of the center54.

From the above description it will be evident that a highly advantageoussawmill has been provided in which the log is suspended from bracketsand the force of gravity will normally maintain such brackets in theircorrect vertical aligned position and therefore very little strain isproduced in the brackets and the supporting frame and such brackets canbe relatively thin so that the sawmill may be used for cuttingrelatively thin lumber.

It will be evident that suitable saw guides may be mounted on the sawsupporting slides 20, 20, 21, 21' to guide the work-engaging edge of thesaw, whereby bending of the saw blades is avoided. This saw guidestructure is conventional and the details thereof are omitted to avoidunnecessary prolixity.

It will be obvious to those skilled in the art, that various changes maybe made in the invention without departing from the spirit and scopethereof, and therefore, the invention is not limited by that which isshown in the drawings and described in the specification, but only asindicated in the appended claims.

What is claimed is:

1. A saw mill comprising a bed frame structure having an elongatedrecess centrally thereof for receiving circular saw blades, a first pairof frames arranged in opposed relation on said bed with each frameextending outwardly from the elongated recess and mounted for slidingmovement toward and away from each other, substantially aligned arborsrotatably mounted on said frames, a first pair of saw blades within saidrecess mounted on said arbors and movable with said frames, whereby thespacing of said saw blades may be varied by movement of said slideframes, means mounted on said bed and operatively connected to saidframes for causing said frames to move toward and away from each other,a second pair of frames mounted on said bed longitudinally of said firstpair; of frames and mounted for sliding movement toward and away fromeach other, a second pair of arbors and saw blades mounted on saidsecond pair of frames for adjustment toward and from each other, anoverhead track supported above said saw blades and extending in thedirection of said recess, a carriage mounted on said track for movementfrom a position clear of said saw blades on the side of said first pairaway from said second pair to a position beyond the cutting edge of saidsecond pair away from said first pair of saw blades, a longitudinallyextending shaft mounted on said carriage below the same and securelyconnected thereto, a first bracket slidably mounted on said shaft formovement relative to said carriage in the direction of movement of saidcarriage and having a lower extremity below said carriage and means forcausing movement of said bracket in both directions, a log engagingcenter on the lower extremity of said first bracket for supporting oneend of a log, a second bracket mounted on said shaft adjacent the otherend thereof and having a lower extremity for adjustable movement alongsaid shaft for accommodating logs of varying length, a rotatable centeron said lower extremity of said second bracket at the height of saidfirst center with means for positively engaging a log for turningmovement about said centers, a shaft connected to said second centerlying substantially in the vertical plane of said centers and having alaterally extending arm, means mounted on said second bracket andconnected to said arm for rotating said shaft a quarter of a turn, meansfor moving said carriage in both directions, an elevating framepivotally mounted on a fixed support for movement from a positionreceiving a log to a position in which a log supported thereon has itscenters in alignment with said centers of said bracket, means for movingsaid frame from its log receiving position to its position for placing alog on said centers, a guide roller mounted on said bed between saidfirst and second pairs of saws and movable from a position below thepath of a log to a position in which it will support a partially sawedlog, and means for moving said roller to either position and means forcontrolling each of said means.

2. The invention according to claim 1 in which each of the said means isfluid operated.

3. The invention according to claim 1 in which the means mounted on thecarriage are gas operated and the other means are all hydraulicoperated.

4. A sawmill comprising a bed, means to mount a saw on said bed, a trackpositioned above said bed, a carriage mounted for movement along saidtrack and past said saw, a pair of arbors mounted in spaced relation andsuspended from said carriage for receiving a log to be sawedtherebetween, means operated on a stationary portion of the sawmill formoving one arbor toward the other to support a log between said arbors,means to move said carriage past said saw so as to carry a log supportedby said arbors entirely past the cutting edge of the saw, means operablefrom a fixed position on the sawmill for rotating the arbor a definiteangle to obtain a second cut on a log, a log elevator comprising a load-1ng frame positioned beneath the carriage for carrying a log from aposition below and clear of said arbors to a position to be supported bysaid arbors, said loading frame having horizontally disposed logsupporting edges positioned in spaced relation lengthwise of saidsawmill and on which a log may roll and having projections to prevent alog from rolling off of said edges whereby the log can be adjustedlaterally in a horizontal plane to obtain vertical alignment of each endof the log with respect to said arbors, means mounting said loadingframe for vertical movement, power means acting on a point intermediateits length to raise said elevator, said frame being flexible to anextent permitting an operator to manually engage the log while said logis supported on said frame adjacent one end and with a small force flexthe frame and thereby position the corresponding end of the log adjacentone arbor so that the one arbor may be pressed against the adjacent endof the log and thereafter the other end of the log can be accuratelypositioned with respect to the other arbor and the arbors moved togetherto maintain the log in the most advantageous position for cutting by thesaw.

5. An elevator for raising logs to be positioned in accurate location tocentering arbors, said elevator including a generally horizontallydisposed slightly flexible frame pivoted adjacent one side and havingits other side movable vertically, power means to apply lifting force tosaid frame at a single intermediate point whereby one end or the otherend of said other side of said frame may be raised while the other endis lowered by a manually applied force adjacent an end whereby a log canbe accurately centered on said arbors, and means limiting excessivesideward movement of a log on said frame while permitting some limitedsideward movement of the log while supported on said frame whereby aperson with a small force can accurately locate the log in a verticalplane.

6. A sawmill comprising a pair of closely spaced saws for simultaneouslycutting an elongated relatively weak timber in which the force of thesawing becomes sufficiently great to cause bending with possiblebreakage of the timber, means to carry the logs past said saws byengaging the ends of the log, and narrow roller means positioned in aplane between said saws while being of sufficient size to support thetimber being sawed within the confines of the space between said sawswhereby 12 timbers of small width and small depth can be cut and meansto move said supporting roller into and out of operative position as'thesawing progresses from the first cut on the timberto the later cuts.

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